The recall occurred after an internal memo from manufacturer Fresenius Medical Care (FMC) was leaked. The memo described a connection between the elevated bicarbonate levels caused by acid concentrates GranuFlo and NaturaLyte and cardiac arrest. FMS sent this memo to its own dialysis centers, but didn’t warn thousands of physicians at dialysis clinics not owned by FMC. The FDA issued a Class 1 recall on March 29, 2012.